1. Field of the Invention
The present disclosure relates to stereoscopic 3D (three dimensional) camera systems. In particular, it relates to a stereoscopic 3D camera system that is reconfigurable.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
There are three known stereoscopic 3D camera systems:
Firstly, there are fixed lens separation cameras in which CCD image chips are fixed at a predetermined distance apart. Many commercially available 3D cameras, including both domestic and professional camcorders, are produced in this way. A typical fixed lens separation system is shown in FIG. 1.
Secondly, there are side-by-side systems with variable separation between adjacent cameras. A side-by-side camera set-up allows for adjustment of the spacing of the cameras. That is to say, the distance between lens centres may be adjusted. When the cameras abut is the closest the cameras can be positioned to one another. A typical side-by-side system is shown in FIG. 2.
Thirdly, there are mirror rigs, wherein two cameras of a 3D stereoscopic rig interact with a 50/50 front beam-splitter. The usual configuration is that one camera looks through the beam-splitter, which comprises a semi-silvered mirror, while the other camera is reflected off it. The advantage of this configuration, in contrast to the fixed lens and side-by-side arrangements discussed above, is that the cameras can operate from zero separation, outwardly. A typical mirror rig is shown in FIG. 3.
Each of these systems suffers from disadvantages. In this regard, it must be noted that the separation (or “interaxial” distance apart) of a pair of cameras affects the depth perceived on a 3D display. For achieving a good 3D effect in a macro situation, such as the filming of an insect or similar, a very small separation is required. In contrast, for achieving a good 3D effect when filming a larger scene, such as a sporting event, a much larger separation will be required.
A 3D camera with a fixed lens separation arrangement, whilst compact, is inflexible when it comes to adjustment of “best-practice” depth management as this can only be achieved by mechanical separation of the pair of image chips or pair of cameras. This is not to be confused with “convergence” or “toe-in”, which is the targeting of the two cameras. In essence, no variable separation is possible with a fixed lens separation arrangement. There are no means for increasing the separation or interaxial distance needed for good 3D.
In a side-by-side arrangement, the closest separation obtainable is determined by the width of the body and/or elements emanating from the camera body. Some broadcast cameras can be quite large, bulky bodied, items, making many 3D filming situations impractical. Side-by-side broadcast cameras are usually used for filming field event sports such as football and rugby matches where the camera-rig must be placed far away from the action being filmed.
In a mirror rig, whilst a zero separation is possible, the camera looking through the semi-silvered mirror loses 50% of the light, while both cameras might suffer from image degradation due to dust, scratches or smears on the surface of the mirror.